Characterisation of binding sites for delta-dendrotoxin in guinea-pig synaptosomes: relationship to acceptors for the K+-channel probe alpha-dendrotoxin.
With use of biologically active 125I-labelled delta-dendrotoxin, a putative K+-channel ligand, homogeneous, noninteracting, high-affinity acceptors (KD = 0.32 +/- 0.07 nM; Bmax = 0.33 +/- 0.04 pmol/mg) were observed in synaptosomes from guinea-pig cortex. This binding was antagonised noncompetitively by alpha-dendrotoxin, an inhibitor of certain fast-activating, voltage-gated K+ channels. Chemical cross-linking of the delta-dendrotoxin-acceptor complex in synaptosomes yielded two specifically labeled polypeptides with molecular masses of 69 and 82 kilodaltons. Although alpha-dendrotoxin prevents the labelling of both these bands, it cross-linked only a single protein with a molecular mass of 69 kilodaltons. It is concluded that delta-dendrotoxin interacts with a distinct site on the oligomeric acceptors for alpha-dendrotoxin.
Muniz
Z M
ZM
Department of Biochemistry, Imperial College, London, England.
Diniz
C R
CR
Dolly
J O
JO
D000818:Animals; D002540:Cerebral Cortex / Q000378:metabolism*; D004546:Elapid Venoms / Q000302:isolation & purification / Q000378:metabolism*; D006168:Guinea Pigs; D007700:Kinetics; D008970:Molecular Weight; D009498:Neurotoxins / Q000378:metabolism*; D015221:Potassium Channels / Q000378:metabolism*; D011950:Receptors, Cholinergic / Q000302:isolation & purification / Q000378:metabolism*; D013574:Synaptosomes / Q000378:metabolism*
D004546:Elapid Venoms; D009498:Neurotoxins; D015221:Potassium Channels; D011950:Receptors, Cholinergic; C042467:dendrotoxin receptor; C020273:dendrotoxin